1. Technical Field
This disclosure generally relates to radiographic imaging systems and methods, and more particularly to methods and apparatus for determining and displaying x-ray radiation generated by radiographic devices
2. Description of the Related Art
The benefits of radiographic devices and procedures to detect and diagnose medical conditions are well documented in the art. A radiographic device typically includes an x-ray tube that is positioned near a patient and a media for capturing an x-ray image. The radiographic device may include various controls that affect the characteristics of the radiation generated by the x-ray tube. Primary among these are a voltage, or kV, control that affects how far the radiation penetrates the target, and a current, or mA, control that affects the number of photons produced by the tube that are ultimately directed toward the target area. Various types of image media are also known A fluoroscope, for example, uses a fluorescent screen to record the x-ray image. Unfortunately, as is also well known, overexposure to x-ray radiation may adversely affect one's health. Accordingly, practitioners attempt to limit or minimize exposure to x-ray radiation by using the lowest voltage and current settings necessary to capture the desired image.
The United States Food and Drug Administration (FDA) has developed regulations that limit the amount of x-ray radiation generated during radiograph procedures, thereby to protect patients from over exposure. Those regulations were recently amended to requite certain radiographic devices to display the x-ray radiation rate generated during a procedure and an accumulated radiation dosage generated over the course of a procedure. For example, under 21 CFR 1020.32, fluoroscopic equipment manufactured on or after Jun. 10, 2006 must display a current air kerma rate and a cumulative air kerma during and after operation of the x-ray tube. The displayed air kerma rate and cumulative air kerma values must not deviate from the actual values by more than 35%. The FDA defines “air kerma” as kerma in a given mass of air. The unit used to measure the quantity of air kerma is the Gray (Gy). For X-rays with energies less than 300 kiloelectronvolts (keV), 1 Gy=100 rad. In air, 1 Gy of absorbed dose is delivered by 114 roentgens (R) of exposure. “Kerma” is defined as the sum of the initial energies of all the charged particles liberated by uncharged ionizing particles in a material of given mass.
In view of the foregoing, it is desirable to provide an apparatus and method capable of determining and displaying both current and cumulative radiation output of a radiographic device.
It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of the disclosed methods and apparatuses or which render other details difficult to perceive may have been omitted It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein.